Even if you only had a passing interest in the Anglo trial, you probably picked up two broad claims in the early days of the prosecution.

The first is that the former Anglo Irish Bank received positive legal advice about the loan for shares deal.

The second is that the Office of the Financial Regulator approved it.

A host of witnesses, chiefly the Maple 10, testified that they had no qualms about the July 2008 deal because Anglo had obtained positive legal advice.

But the jury were suddenly told by Judge Martin Nolan on day 18 of the trial that they must disregard any evidence of legal advice as irrelevant, a ruling that changed the course of this already landmark prosecution.

It is a ruling that has struck fear into the heart of company directors who routinely rely on legal advice to ensure compliance with the Companies Act.

Judge Nolan's ruling followed more than a week of intense argument in the absence of the jury that had nothing to do with banking and much ado about absolute, strict and ordinary liability in Irish law.

A previous row about absolute liability led to the striking down, by the Supreme Court, of a key statutory rape law – because a man could not claim he was mistaken about the age of the young girl he had sex with.

Almost 40 convicted paedophiles unsuccessfully sought their immediate release in the wake of the 2006 CC v Ireland ruling which led to the introduction of emergency underage sex laws to protect young people.

During their trial, Sean FitzPatrick, Pat Whelan and William McAteer also queried whether they could, in the wake of the CC case, be convicted and jailed for up to five years in the absence of a criminal intent.

They wanted to point to the fact that legal advice was taken by Anglo to prove that they, as officers of the bank, did not have 'mens rea' or mental intent.

CONTENT

The issue of whether they could point to the fact that legal advice had been obtained, let alone whether its contents could be revealed, dogged this trial long before it even began.

For FitzPatrick, Whelan and McAteer, what mattered was not whether the content of the legal advice was good, bad, mistaken or brilliant.

But the men wanted to show that the taking of legal advice was a reasonable step, one that would bring them within the realms of a good faith, reasonable care or due diligence defence in a court of law.

They complained that any refusal by Judge Nolan to allow the jury to consider the fact of legal advice implicitly rendered Section 60 of the 1963 Companies Act as an absolute liability offence, where no defences are available.

Another "worst-case scenario" posited was that the section would be regarded as a strict liability offence, albeit without the benefit of being able to rely on good faith or reasonable care.

Another provision of the 1963 Act also prevailed in legal argument. This was section 383 (2), a catch-all provision which applies to each and every offence under the Companies Act.

This section states that an officer shall be presumed to have permitted a default by the company, unless the officer can establish that he took all reasonable steps to prevent it – or by reason of circumstances beyond his control, was unable to do so.

In argument, the defence complained that they could not rebut this presumption by showing that the taking of legal advice was a reasonable step. In the end, Judge Nolan ruled, in line with the cardinal principle that ignorance of the law (as distinct from the facts) is no defence, that no legal advice could be admitted because it was irrelevant.

The legal advice disputes dominated much of the legal argument and led to calls, refused, for Judge Nolan to discharge the jury.

Some of the country's best trained legal minds made submissions on the issue, which could yet form grounds for any future appeals.

It could also strike fear into the hearts of directors who may be wondering, after the Anglo trial, if they can derive the same level of comfort that they previously did from legal advice.